Radio relaying system



Allg-*14,1945l c. w. HANSELI..` 2,332,414

RADIO RELAYING SYSTEM Filed Jan. '7, 1945 ZSheetS-Sheet 2 nfPfA fR RfPf/l TER snr/0N A. n STA r/o/v 1 QL, E@ .41?,

ATTORNEY poration of Delaware 'This invention relates to improvements in radio l relaying systems. C Y ,t 1n settingup a long series ofjstandardized radio relaytstations,"such` as might be used for televisionfor example, there would normally be used standardized masts or towers ofthe` same `di`4 mensions'at, all repeater stations for both the transmitting and receiving antennas.` Since the transmission lines Vbetween the repeater appa` ratus `(customarily located near the ground)` and thejtransmit-,ting` andreceiving antennas would tend to havethe same 1engths,r therejwould be,4

conseqlience thereof,- a tendency lfor addition) of're'ection effects upon the useful modulation." .'.Ihe primaryobject of the present invention is topreyentcilimulative distortions in repeater stations or fa Y.radici relay, system brought about" by Wave freilectins Von transmission lines at these statiodns' i t ,t t n t. .d

@Itis proposed to accomplishthe results of the inventiont.by` deliberately varying the lengths of'k the; transmission lines 'carrying radio frequencyy currents.at,the. .diierent stations, in order to fobdiffreht time deiaysfor yreflectedWaves, in atffmalnnerf to; avoid 'adding up' reection effects an,iilhtliil'is4 fvoid producing multipleimages `or `had distortion.` This can be doneby making, the

. transmissiiqnllines at one station "differ fin length mini iz'ef thej distortions du'e` to Are'ectio'n ytyp juggling the lengths` of.' individual transmission lirreslovera range offene-,quarter wave length of the carrier-Zzcurrent.:` i f.- d @@Ifgn practice-,itis found that the'reflections are. ,Qtiisnicieetlr constant if" Permit .distortion by thisfsrnall range of transmission line lti n, then-it is proposedltdfmake greater differences in transmission? line tortions scattered outwith respect 'to time s. NPAT d 2,382,414 nemo-Reuma SYSTEM Clarence W. Hansell, Port JeffersonQN; Y., as-

signor to `Radio `Corpora 'lenethsin ord ENTDFFIC lays "may be. produced due to rel`ections,-:as "a consequence of which` there will not be an ampli'y tude addition of the reected `rncdulationcoirjif d Wliic'h will consequently be mnch less noticeablef'; jf A better understanding offthe invention may be had Vfrom a reading of the follotving' desctrip-J` tion which isfaccompaniedwby'drawings i'irliereiril Figs 1 and 2 illustrate how the principles dijthe inventioncan `be Drilled4 to` t'vvo 'different tyDesoi repeater stations in aradio relaying 'systeii'i,` andl Figs. 3 and 4 illustratetheprinciples uof*` the ini I i tionsmina radiorelayingsystemi i Referringto Fig. 1 in more4 vdetail,thereis shown one repeater station typical of agroupL or similar repeater stationsoffaradio relaying vention applied to af'pluralityfoyf repeater""staw 20 system; This repeater station comprisesfapair" o i similar masts I and 2 for re'spectivelysupport--` ingi` receiving antenna VR transmittingffam* i temav Tfat locations yhighly "elevated `with` respect to ground; The receiving and transmitting am 25 tennas R and Tare merelyillustrativeof any suitable `1 equipment for receiving?K and radiating waves,' andl 'are showny herein conventio'nallyy f including a parabolic antenna with thedipole arrangement ator nearthefocus of the parabola;1 The receiving antenna R' on the topeflmast 1| is" connected by means `of transmission 1ine`--A"`ft'o the input of repeater, apparatus VM "Whch^i lo# cated at `'or near the ground. The` outputI if repeater `apparatusM `is connected" by means of` line B to thetrtmsmitting` ahtenn'afr at thltop' tute any suitable e1etroi1 discharge device ampiiv u theputput'ofitherepeater DuetotlfieviiriL` pedancefmi'smatch between lines A "and Biand their respective terminal apparatus, there areie lections onftheV lines Anandl Biwhich WillKater t time delays determined by Ithe lengthfof theiline) either 'add `to` or oppose thefincoming 'and/or out;

t going mainV signal Waves;` Thus, in iline the mismatch between the impedance vnf this line "and the receiving antenna andthe repeater will cause delayed -reected waves of incoming"` energyito gccur on theline `A which may'add tor oppose the main incoming wave.

ter,v wavelength (on.y anj. odd number y match between the impedance of line B and the terminal equipment'comprising transmitting antenna T and the repeater apparatus M will cause ldelayed reflected waves of outgoing energy to occur on line B which may add to or oppose the main outgoing wave. The reflections in both lines A and B may'addo nppose eacirjetnertinsoffargas the signalmodulation dist'rtionis concerned-ffln television, such distortion produces multiple or ghost images. These distortion effects 'can be quite pronounced if `all repeater or relayfstationsn areStandardiZed as to tower lengths aridlo'cations of similar piecesl of equipmentsfand allythese pieces of equipments are madefto fbealike: There? thus exists the probability in the case of completely standardized equipmenttat all stations,

that the reflections at all the' repeater stations maycause additive distortions. ffii In accordance withy the rpresent invention* .the

lengths of linesAandsB'natany one repeatf station are made ',Jdier'ent from fthe same .0.1

similar lines at another repeater station," and this difference is preferablylelectrically neQ-gua Fig. v3. lIt is alsofpreferredthat the line VA be made to differ in lengthirom thelinelB at theY same repeater station alsoby onequarter 2v'vz'aalef length (or anoddnumberof,quarten Wavelengths dierence, Y reverses.; ,the polarity .lof .the 4distortion and thusitispossible forthe distortion produced at the` same.. station to, balance .out-,fr and the distortions lat adjacentjstations also( to balance out.

VI-f desired; thelinesAand Bpf veach r.elay`.sta tion could bemadetofdifferelectrically legione-Q eighth wavelength, or an integpral'number-.Yothalfi' wavelengths `plus or minus ,one-eighth. wave;-

length, in which-casethere .cannot beeither addi-3 tion or opposition ofthe ydistortions'produced.byI

lines A and B ofthe samefstation'.H

Fig. y2 shows amodifled arrangement. cfa ypef.l of repeater station wherein the-receivingantenna Ris connectedf`fby` means of;transmission.line*CA to receivingfanddemodulating 4means F located: at or near theground.: "Similarlythe..transrnit. ting antennaTflQCated jat the .topoi `1another` similar tower is connected by lineUD 'to transmit.-y ting and re-modulating equipment G also located at or-near the ground. The output or the equip;

ment F is connected-,tothe input` ofrjthe equip-l ment G by way, of .atvideo Aor.modulationrre-f 55 y quency `cable yEQvr/h,ichf may. ,beloneTquarter to one-half mile iin-length.`l Thus, lines C andrD' carry radio frequency currents, whilevideo cable E carries a much vlower freq11enycurrent.A A lternatively, 1in a, manner; know-n Lthe artgthe high frequencygenergy received by` antenna R, and deliveredv 110. the @Csi-verand; fmdlllatol" over line C may be changed by a suitable local hetero@` dyne or beating oscillatortoflower7 frequencycurrents which maythen bev transmitted .t over the cable E to the transmittingand.,remodulating equipment G where another locallbelating, oscillator and suitab1e-,sing1ersdeband;.lieS -Pflui radio.y frequency..`currents for transmission over the line D'tothe transmittir1g antenna T 1 l In order to preventadditive distortions inthe case of Fig. 2,'it isdesired-thatthe video-orlowver frequency cables at`v .the ,different. repeater sta,-

tionsbe of differentl lengths. ItL should-herab@ 4 n t n 75 radiator to the input of the demodulator and the noted that there is no continuous radio frequency Similarly, the ms- 1 questa. Y wavelengths) at the Opsatgfreqilncyn. Note.l

5 station to the other as economically feasible, and

that lines C and D at each repeater station should differ electrically from each other by oneeighth wavelength 3( or an integral number tfof half wavelengths'zplus :or minus oneeighth` wavelength) at vthe operating frequency. Also, that i "fthe mean length of the lines C and D at any one repeaterstation should differ electrically by oneeighth wavelength or by an integral number of alfwavelengths plus or minus one eighth wavel ffleng'ththereoff'from the mean length ofthe sar'ieliries'iatfany.other repeater station in the 4radiorelay chain. ,This is shownin Fig. 4.

' Altrio'ugl'l separattowers have been shown for f3* supporting transmitting and receiving antennas; .$.20 it should be understood that a single'tower may be' used in some'cases tosupport both. 4kWhat is claimedis:

17... Afra'dio repeater station` comprising'a receiving` energy collector andI a separate transinitting energy radiator, means, for. supporting said energy lcollector `and said radiator atal distanceY above ground, electron Y* discharge device translation circuits located at or near the ground,`

f., andradio IreClllc-mcy lines which differA electricall5v --f mene-quarter wavelength or aneddnumber'oflengths) electrically attheoperating frequency. j This odd number f of electrical t.. quarter.` wavel quarter wavelengths at the operating radio fre` quency Vconnectingsaid energy collector yand said' radiatorv to different `parts. vof` 'said 'translation 2;.y `nl radio .repeater station 4ceiripr'isir-" ii;f af freceiving energy collector.and` aseparate' transmitcircuits.Y i

y tingy femment; means ,fer Asupporangf sairi energy' couectorad said `transmitting element atA een;

tance..,above ground,electron vdischargejr` device translation fllflliisllotatticiv atorfnsarihsrgund. angl-radio frequencyf lines' which diill'erjV electri-f` callynby one-.eighthwavelengtn or, b yfan' in-y tegrarnnmber of nai'fzwavelengthspits1er minus' oneeighth wavelength, at theoperating radio frequency connectingTsaid. energyy collector and' said transmitting'lelenient' to diier'ent parts of' saidtranslationcircuits.`

i 3.A radio repeater 'station comprising a re# ceiving energycollector and a-transmitting radi-v er gy collector`;andsaid transmitting radiator to' said input land t outputl circuits, respectively,`jthe` lengths of `said linesubeing `such that reflection effects-occurring inlone line are substantially cancelledby-re1lection effects occurring inthe thr=rr t1i neV l 4.1A. radio repeaterf stationl comprising Ya re;-

\ ceivingenergy collector and a transmitting radi)- atorfspaced therefromand effective in a different direction,individual masts supporting said-energy collector-land said radiator',I anelectron discharge device modulator circuit near the foot of ythe mast "76 supporting said receiving energy collector; ani

e'lecftron;A ldischarge device l`-reinodulatork device near theio'otof'the other-Vmastg'radio frequency carrying 'lines of diierent electricallengths con-l necting' the receivingr collec'ztorl and transmitting aesaem output of the re-modulator, respectively, and a `cable connecting together the output of said demodulator and the input of said re-modulator, said cable carrying currents of lower frequency than the frequency of the currents carried by -said radio frequency lines.

5. In a radio relaying system, a plurality of radio repeater stations, each of said repeater stations having a receiving energy collector and a transmitting radiator each eifective in a difierent direction, individual masts supporting saidV -v'energy collector and said radiator, an electron discharge device demodulator circuit near the foot of the mast supporting said receiving energy collector, an electron discharge device re-modulator device near the foot of the other mast, radio frequency carrying lines of dierent electrical lengths connecting the receiving collector and transmitting radiator to the input of the dmodulator and the output of the re-modulator, re-

r s'pectively, and a cable connecting together the output of said demodulator and the input of said re-modulator, the mean length of the radio irel-quericy carrying lines at one repeater station 'idiiering from the mean length of the radio iredistance above ground, electron discharge device v circuits, the mean length of the lines at one repeater station diiering electrically from the mean length of the lines at the other repeater station by approximately an odd number of quarter wavelengths, including one-quarter wavelength,

- '7. In a radio relaying system, a pair` of radio repeater stations, each having a receiving energy collector and a transmittingradiaton means for supporting said energy collector and said radiator at the same appreciable distance above ground, electron discharge device translation circuits located at or near the ground, and radio frequency lines of different electrical lengths connecting said energy collector and said radiator to said translation circuits, the mean length of the lines at one repeater station diering'electrically from the mean length of the lines at the other repeater station.

8. In a series of radio relaying stations each having transmitting land receiving antennas individually connected to vacuum tube translating apparatus by means %f transmission lines, the

`method of reducing signal distortions due to reilections on transmission lines which comprises makingv different adjustments ofthe lengths of said lines at the several stations to prevent addition of distortions.

CLARENCE W. HANSELL. 

